pruden



H, B. PBUDEN. COMBUSTION 0F POWDERED FUEL. APPLICATION FILED MAY22. 1916.

1,307,375. Patented June 24,1919.

2 SHEETS-SHEET I.

mmvmn.

H. B. PRUDEN.

COMBUSTION 0F POWDERED FUEL. APPLICATION FILED MAY 2 2- I9I6.

2 SHEETS-SHEET 2 INVENTUR Patented J une 24, 1919.

GOIVEE'U "'ii N 93? FUEL.

To (ll/6 whom it may cont rem:

Be it known that I, liARR'K l3. PRUDEN, a citizen of the United States, residing; at Chicago, in the county of Cool; and State of Illinois. have invented certain new and use-- ful Improvements in the Combustion of Powdered Fuel, of which the following is a specification. l

The object of the invention is to provide a processin which the fuel is difiused and suspended in the proportion of air best adapted to secure complete combustionwithout excess thereof so that each small particle is immediately surrounded with the amount of air required for its combustion, with the result that when the air charged with fuel enters the furnace. or oth -.r plan of consumption where the necessary temperature for combustion is provided, the mixture at once ignites and begins to burn throughout its volume, and continues to burn in a so called lazy fiance, without the supply of additional air until is completely consumed. lVith this object in view I maintain a reservoir or supply of air con taining a substantially uniform amount of fuel in suspension and which for this pur pose is kept locally in quite violent a ation, but has no n'iovenient of transla on except as it is steadily drawn upon to s1 ply the burner. In the preferred method of practising the invention disclosed in the following specification and the accompanying drawings, the reservoir or supply of fuel laden or carhureted air is maintained adia cent to and beneath a mass of powdered fuel by a jet or ets of air which traverse the car hurried air and maintain the same a s e of agitation to prevent the deposition of the fuel carried thereby, and impinge upon the mass of powdered fuel carrying away apertion thereof. thus constantly replenishing the supply of caroureted an: Qthei P-IiUll" as the latte is drawn upon to supply coin-- bustion. The carbureted air in tlie reservoir is too rich in fuel for complete and perfoot combustion and therefore before it is fed to the furnace or other place of combustion it is mixed with an additional supply of air which is added to the carbureted air in such a manner as to be thoroughly comniingled therewith and to give a slight whirl or cyclonic motion thereto without substantiallyincreasing its forward velocity. In

the foregoing I have referred to the cone bustion of the carbureted air in a furnace Specification of Letters Patent. Patentgfl June 24, 1919. application 25% 1916. Serial it'd. 93,013.

but it will be understood that the process is applicable to the preparation of carbureted air Wherever solid fuel is employed and Whether it be burned in a-furnaee, internal combustion engine, turbine or any other combustion apparatus;

in the accompanying drawing 1 have shown and in the following specification described in detail an apparatus which is designed and adapted to carry out my improved process. It is to be understood, however, that the process is independent of any specific apparatus for carrying it out and that the particular apparatus described is disclosed only for the better elucidation of the improved process. Moreover, the

specific disclosure is for the purpose of one emplification only, the scope of the invention being set forth in the following claim "n which I have endeavored to distinguish it from the prior art so "far known to me, without, however, relinquishing or abandoning any portion or feature thereof.

in the accompanying drawing, Figure I is a substantially central, section, through a portion of a preferred form of apparatus for ca p out my invention; Fig. 1 a continuation thereof; 2 a see- .ion upon the line 22 of Fig. l and Fig. 3 is an enlarged fragmentary detail on the plane of Fig. 1.

The hopper 3 is frusto conical in shape, and has a perforated bottom 1 covered by a screen of wire mesh of a size suitable to properly support the fuel therein, but o permit limited quantities thereof to pass through the perforations, see Figs. 1-"- and 3" have found a n h of about one-sixteenth inch to answer the purpose satisfactorily. The fuel is fed into the hopper through an opening and rests upon the bottom thereof. bridging; or arching of tne fuel being prevented by the shape of the hopper pre- ViO'l'iSly described. lreep the fuel dry in order that it may properly mix-with the air, and for this purpose til we provide a vacuum jacket 7 suitablyspaced from the wall 3 of the hopper, the

' concave upwardly and surrounds the upper end of an air supply conduit 9. The bottom wall a 18 also formed with a concentric curved outlet pipe 13, the other end of which passes through the conical walls 3 and f the hopper and jacket respectively, as at 14.- and 15. The lenticular space between the perforated bottom 5 and the imperforate bottom 8 is divided by a horizontal. partition plate 16, mounted upon or formed integral with spider 10, which comprises a series of two or more posts longitudinally perforated to receive the bolts 17, by which the structure including bottom 8, the spider, perforated bottom i, and the casting 12, are secured together.

Nozzles 18 in the division plate 16 are ar ranged one opposite each perforation in the bottom wall 4, and the partition 16 is further provided with a concentric opening 19,

in which is fitted and held a nozzle 20, communicating at its flared lowered end with the inlet pipe 9, and opening at its reduced upper end into the outlet pipe 13. Surrounding the nozzle within the end of the pipe 13 is a venturi 35 which is preferably detachable so that it may be replaced when desired by a venturi of a dill'erent size ac cording to the amount of carbureted air to be fed to the burner. 'lhepartition 16, therefore, divides the lenticular space between the perforate bottom. 5 and the inn perforate bottom 8 except for the passages formed thcrethrough by the nozzles 18 and the central nozzle 20.

The operation of this portion of the device is as follows:

In the hopper 3 is maintained a body of very finely divided. pulverized fuel which may fill. the same if desired. The body of fuel rests upon the screen upon the perforated bottom L, which screen is, as heretofore stated, of such fineness as to permit the pulverized fuel to pass therethrough a little at a time, but to prevent the mass from pass-- ing thcrethrough so as to fill up the space beneath the perforated bottom. When air is forced into the pipe 9, it is diffused through the chamber beneath the partition 16, and is forced through the nozzle therein. impinging upon the-screen over the perforations in the plate 4, and also upon the bottom of the body of pulverized fuel supported on said screen. The pulverizedfuel. immediately acted upon by the jets of air is set inmotion and either by the eddies of air caused by the jets striking against the body of fuel, or by its own gravity or both sifts through the screen into the supply chamber or reservoir immediately above the partition 16, where it is thoroughly mixed with the air by means of the numerous small jets 1S,

and so carburets the air and is suspended therein. The space around the nozzle 20 freely communicates with this reservoir or supply of carbureted air, and the small stream of air issuing from the nozzle exerts an injector action upon the carbureted air in the reservoir, drawing a constant supply for the burner.

The carburetcd air so furnished is, however, too rich in fuel for efficient combustion, and therefore before it reaches the burner we supply it with a suitable additional volume of air which is thoroughly mixed with the carbure'ted air in such a way as to impart little or no forward velocity thereto, but to keep it in sufficient agitation to prevent the settling of the powdered fuel. For this purpose the main air supply pipe 9 is provided with a branch 21 which cominunicates through a valve chamber 22. with an air chamber surrounding. a slightly expanded conical portion 24 of the outlet pipe 13. The expanded portion 24 of pipe 13 is perforated as at 25, the perforations being provided with spirally arranged lips or wings 26 (see Fig. 2), which are so located with reference to the openings asto tend to give the air flowing therethrough a cyclonic motion as it enters the enlarged end of the pipe 13. Within the latter is arranged a conical perforated diffusion screen 27, thOl apex of which extends toward the incoming current of carbureted air, and the base of which is toward the furnace opening shown at 28. Thus the supplemental air coming from the branch 21 of the air supply pipe enters the enlarged end of the pipe 13 with a cyclonic motion and mingles with the carbureted air coming from the reservoir beneath the hopper, and the mixture is furthered by the perforated difi'usion cone 27, which also has the effect of checking the inertia of the mixture so that it arrives at the burner in a thoroughly mixed condition, but with little inertia and low pressure.

In order to insurethe proper proportion of the air to the fuel, I provide in the valve chamber 22, a valve 29, shown as a sleeve valve, which is operated by a rod 30, connected to an elastic diaphragm 31, which is exposed upon one side to the pressure of the pipe 9, the chamber 32 being connected to the latter through the branch for this purpose. A spring 34 opposes the pressure on the diaphragm. The construction is such that with the increase of pressure in the pipe 9 the valve 29 is more fully opened to admit air to the chamber 23. the opening of the valve being of course proportional to the pressure in the conduit 9. The entrance of the air into the conduit 9 is controlled by a gate, or valve 38, which may be controlled in any suitable way as by asolenoid 40, the current through the latter being controlled by a hand-operated rheostat or otherwise.

The operation of the several parts of the device have been described in connection with the construction. We will point out, however, that the air supplied through the nozzles 18 maintains within the chamber directly above the partition plate 16, a body of air carbureted with pulverized fuel, which is constantly drawn upon by the injector nozzle 20 to supply the burner. The constant action of the jets from the nozzle 18 maintains the mixture of fuel and air in the reservoir locallv constantly in motion so that there is no tendency of the solid particles to separate out, but on the contrary they are thoroughly mixed with and surrounded by air. When this ca'rbureted air reaches the air chamber 23.; i t-is mixed with a further supply of air so that each particle thereof is surrounded with the precise amount of air adapted "to most efficiently support combustion, and the carbureted. air is fed to the burner in this fully mixed condition, and without any envelop or additional supply of air. It enters the burner ing it to the place therefore in a perfectly homogeneous condition in the proper proportion of fuel and air to best support combustion, and with only such' motion as is necessary to keep up the supply to the burner and avoid the settling out of the fuel.

I claim:

A method of preparing powdered fuel for combustion which consists in maintaining a mass of powdered fuel in an inclosed space causing jets of air to impinge upon the fuel across an air space adjacent the fuel thus creating and maintaining a body of fuel-laden air in contact with said mass of powdered fuel, and agitating the fuelladen' air continuously to prevent precipitation of the fuel, and continuously drawing a supply of the mixture therefrom and feedof con'ibustion.

HARRY B. PRUDEN. 

